Insulated wire and process therefor



Jam 31, 1933. s. RUBEN 1,896,043

INSULATED WIRE AND PROCESS THEREFOR Filed Dec (5,"1930 INVENTOR ATTORNEY Patented Jan. 31, 1933. I

UNITED STATES PATE OFFICE SAMUEL RUBEN, OF NEW ROCHELLE, NEW YORK, AssIoNOR To VEGA MANUFACTUR- ING CORPORATION, OF WILMINGTON, DELAWARE, A CORPORATION OF DELAWARE INSULATED AND PROCESS THEREFOR Application filed December 3, 1930. Serial No. 499,845.

a wire having a flexible refractoryinsulation.

A further object is the provision of a wire having a closely applied flexible Insulating coating containing refractoryinorganic l0 material una flected by high temperatures.

Other objects will be apparent from thedescription of the invention and from the drawing in which is shown an insulated wlre made in accordance with the invention.

I have found that in order to properly coat a wire with an insulating material having the desired characteristics, it is desirable also to have, (1) a flexible binder of the resinous type to give a proper bond at low temperature and (2) a further binder, which material is to be effective at high temperatures. This second binder must be of the inorganic type such as boric acid or lead borate and it serves two important purposes: one, it binds the refractory and insulating material at high temperature two, it prevents scaling and surface oxidation.

The coating may consist of a refractory oxide, a gum or resinous binder and a borate or other inorganic relatively high temperature bindingagent.

The insulating or refractory material used in the coating of this invention may consist of one or more of the refractory oxides, for example, chromium sesqui-oxide, aluminum oxide, magnesium oxide, beryllium oxide, titanium oxide, zirconium oxide or combinations of these, the chromium oxide, however, being preferred. I may also use other compounds containing the silicates, such as beryl or mica. The material used should 7 be ground to as fine a state as possible.

As a flexible binder of the resinous type I prefer to use shellac and Venice turpentine in a volatile solvent such asalcohol or amyl acetate. For the relatively high temperature binder I prefer to use boric acid.

In the coating of some wires, notably cop-- per, in order to have the insulating coating adhere to the copper and prevent surface oxidation effects, I have found that it is desirable to preliminarily coat the Wire with a coating that is integral with the base and preferably fused thereon, such as a solvent oxide coating. For this purpose I have found that a fused on layer of antimony oxide is especially suited; or the wire may also be treated by passing it through a borate solution and heating it, whereupon (if copper) it acquires a hard red fused surface.

In a typical coating mixture I use 200 grams of chromium sesqui-oxide, 100 grams of boric acid, 100 grams flake shellac, 100 grams of Venice turpentine and 450 cc. alcohol. The shellac is first dissolved in the alcohol after which the chromium sesquioxide and boric acid are added. This mixture is milled until the various materials are throughly ground after which the Venice turpentine is added and throughly admixed. The solution is then ready to be used. The figures given for the composition of the coating may be varied by increasing or decreasing the respective amount of its constituent elements according to the nature of the coating desired; it being recognized that in some cases less flexibility and greater insulation or vice versa may be desired.

The process used is that of a continuous coating whereby the wire is passed through a mixture of antimony oxide in alcohol, then into a furnacewhich dries the mixture and melts it. The fused antimony oxide flows over the surface of the wire and when cool presents a tough integral layer of minute thickness. The wire then passes through cups containing the insulating compound, be-

ing heated and baked, in furnaces located between the cups, to a temperature just below that at which the coating darkens. During the heating, the inorganic binder, of boric acid melts and binds the refractory. oxide crystals, a great part of the organic materials being baked ofi. The thickness of the'coat ing is regulated by the consistency of the solution, the speed with which the wire passes through the coating cups, the number of cups used, the temperature of the furnace and the size of the wire. Even though the wire may be heated to a point where the organic bindor is disengaged no harm results due to the presence of the inorganic binder, boric acid. The use of this borate in the coating also dispenses with the necessity of a flux in soldering the wire, particularly when copper wire is coated.

Vhile the initial process of fusing on a layer of antimony oxide is desirable, it is not necessary, and fairly satisfactory wire can be produced without this initial step.

In some cases in order to further moistureproof the wire and to increase its flexibility a thin finish coating of lacquer or enamel may be applied.

In the drawing, the insulated wire 1) is composed of copper base (2) having formed thereon an integral oxide coating (3) upon which the insulation (4) has been coated. Covering this insulation is waterproof lacquer coating (5).

I claim:

1. An insulated wire comprising a metal base, an oxide coating formed integral with said base, and a coating of finely divided insulating material upon the first coating and held in position by a binder effective at low temperatures and a second binder capable of standing a red heat.

2. An insulated wire comprising a metal base, a fused layer of antimony oxide upon said wire, and a coating of finely divided insulating material held together and upon said wire by an organic binder effective at relatively low temperatures and an inorganic binder capable of standing a red heat.

3. An insulated wire comprising a metal base, a layer of fused oxide integrally formed upon said wire, and a coating of finely divided insulating -material held together and upon said layer by an organic binder and an inorganic binder composed of boric acid.

4. In an insulated wire a copper base, a fused layer of oxide formed integrally with said base, and a coating of finely divided insulating material upon said layer and held together by an organic binder composed of shellac, Venice turpentine, and alcohol and a second binder of boric acid.

5. An insulated wire comprising a metal base, a fused layer of antimony oxide upon said base and formed integrally therewith, and a coating of finely divided insulating material held together and upon said base by an organic binder and a second binder capable of standing the temperature of red heat, and a coating of waterproof material upon said insulating coating.

6. An insulated wire comprising a copper base, a layer of a fused oxide formed integrally upon said base, a coating of finely divided chromium sesqui-oxide upon said layer and held together and upon said layer by an organic binder and an inorganic binder capable of standing temperatures at red heat, and a surface layer of a moisture-proof material upon said coating.

7. The process of insulating a wire which comprises dissolving an oxide in alcohol, coating the wire with a layer of the dissolved oxide, heating the wire so as to fuse the oxide integrally with the wire, mixing the insulating oxide with an organic binder and with an inorganic binder capable of standng a temperature of red heat, successively coating said mixture upon the wire to form a layer thereon and heating said wire so as to dry the layer, until the desired thickness is reached, and coating said second layer with a layer of moisture-proof material.

8. The process of insulating a wire which comprises coating the wire with antimony oxide dissolved in alcohol, heating the wire so as to fuse said oxide to the wire, mixing an insulating oxide with Venice turpentine, shellac, alcohol, and boric acid, applying a plurality of coatings of said mixture upon the fused oxide layer on the wire, heating said mixture after'each coating so as to dry it upon the wire, and applying a surface coating of waterproof material to the last coating.

Signed at New Rochelle in the county of Westchester and State of New York this 2nd day of December A. D. 1930.

SAMUEL RUBEN. 

